We　described　a　method　for　measuring＇　3D　position　and　orientation　of　endoscopic　probe　using　magnetic　field.　We　derived　particularly　three　expressions　of　magnetic　field　generated　respectively　by　three　mutually　orthogonal　coils,　and　also　derived　three　expressions　of　the　magnetic　induction　signals　obtained　by　three　mutually　orthogonal　magnetic　field　sensors　attached　to　the　endoscope.　Then　we　constructed　6D　nonlinear　equation　group　(including　3D　positions　and　3　attitude　angles),　and　adopted　Newton-Laferson　arithmetic　to　solve　the　equations.　Finally,　we　could　get　the　3D　position　and　orientation　(x,　y,　z,　a,　b,　c)　by　using　original　data　obtained　from　magnetic　sensors;　and　could　thus　realize　3D　localization　and　navigation　of　probe　during　endoscopic　diagnosis.